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From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
To: Sasha Levin <sasha.levin@oracle.com>, Mel Gorman <mgorman@suse.de>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>, Linux-MM <linux-mm@kvack.org>,
        Hugh Dickins <hughd@google.com>, Dave Jones <davej@redhat.com>,
        Rik van Riel <riel@redhat.com>, Ingo Molnar <mingo@redhat.com>,
        Kirill Shutemov <kirill.shutemov@linux.intel.com>,
        Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [RFC PATCH 0/7] Replace _PAGE_NUMA with PAGE_NONE protections
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References: <1415971986-16143-1-git-send-email-mgorman@suse.de> <5466C8A5.3000402@oracle.com> <20141118154246.GB2725@suse.de> <546B74F5.10004@oracle.com>
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Date: Tue, 18 Nov 2014 22:26:41 +0530
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Sasha Levin <sasha.levin@oracle.com> writes:

> On 11/18/2014 10:42 AM, Mel Gorman wrote:
>> 1. I'm assuming this is a KVM setup but can you confirm?
>
> Yes.
>
>> 2. Are you using numa=fake=N?
>
> Yes. numa=fake=24, which is probably way more nodes on any physical machine
> than the new code was tested on?
>
>> 3. If you are using fake NUMA, what happens if you boot without it as
>>    that should make the patches a no-op?
>
> Nope, still seeing it without fake numa.
>
>> 4. Similarly, does the kernel boot properly without without patches?
>
> Yes, the kernel works fine without the patches both with and without fake
> numa.


Hmm that is interesting. I am not sure how writeback_fid can be
related. We use writeback fid to enable client side caching with 9p
(cache=loose). We use this fid to write back dirty pages later. Can you
share the qemu command line used, 9p mount options and the test details ? 


-aneesh